"The supporting players are the interesting ones, but the whole thing's fun."

In some cultures, it's perfectly normal for men to live at home until they get married, no matter how old they are when that finally occurs. Tripp wishes he lived in one of those places.

Tripp (Matthew McConaughey) is the happy-go-lucky 35-year-old at the center of "Failure to Launch," an occasionally very funny but also very sloppy quasi-romantic-comedy from director Tom Dey ("Showtime," "Shanghai Noon"). Apart from being named "Tripp" and still living with his doting parents (Kathy Bates and Terry Bradshaw), Tripp has no strikes against him. He has a decent job as a boat broker (like a Realtor, except for boats), he's physically fit, he dates often, and he has normal hobbies.

He knows it's considered dorky to live at home when you're 35, but he doesn't care. In fact uses it to his advantage: Anytime a woman starts to get too close and commitment-oriented, he chases her away by revealing his living situation. Works every time. His best friends Ace (Justin Bartha) and Demo (Bradley Cooper), also 30-something home-dwellers with no other major social flaws, have pointed out that Tripp sabotages every relationship he has, but since when do men take relationship advice from other men?

Tripp's parents, love him though they do, want him to spread his wings and get the hell out. To that end, they hire a woman named Paula (Sarah Jessica Parker), a sort of relationship hooker whose specialty is getting men to move out of their parents' houses. Seems like a narrow niche to me, but I guess she knows what she's doing.

What Paula does is "accidentally" meet the guy you've hired her to deal with, charm him, date him, then boost his self-esteem to the point where he decides to move out of Mom's house and get a place of his own. (All these guys really need is a little self-confidence, Paula theorizes.) Once that's accomplished, Paula remorsefully breaks things off, lets him down gently, and everyone's happy.

And there's your premise. It goes without saying that Paula will ACTUALLY fall in love with Tripp, that Tripp will eventually learn of her initial deceit, and that at least one pivotal scene will take place in the rain. The screenplay, by TV writers Tom J. Astle and Matt Ember, clings to the romantic-comedy formula at all costs, and sometimes with ridiculous results. You know how the big reconciliation scene at the end of these things always takes place in public, usually at an airport or on live TV? Well, Tripp and Paula's happens in a private room with no witnesses; luckily, Ace has installed hidden cameras and microphones so that he and the other interested parties can watch it on the big screen at a local coffeehouse. After all, if the scene didn't occur in public, the movie would be in big trouble with the Romantic Comedy Police.

What's surprising is the film's dialogue, which is peppered with snappy exchanges. The MVP is Zooey Deschanel, who plays Paula's bitter lush of a roommate, Kit. In a truly kooky subplot, Kit is tormented for much of the film by a mockingbird that lives outside her window. Her efforts to get rid of it lead to this exchange with a sales clerk at a gun shop:

"You can't kill a mockingbird!""Why not?""Well, for one thing, there's that book, 'To Kill a Mockingbird'!""OK, I'll take a copy, right here.""No, it's not an instruction manual.... How do you not know the book 'To Kill a Mockingbird'?""I know other things."

Kit's interaction with Paula is also very funny, as when Paula comes home to find her drinking and Kit explains:

"It's champagne Thursday.""But today is Friday.""Champagne Thursday came twice this week.""Ah, for the third week in a row.""Yeah, they're thinking of making it permanent."

That's good stuff, people! The average rom-com doesn't usually bother with such glib, quotable dialogue.

But there are problems, too. The film doesn't let anyone have any real emotions, because they're always being jerked around. Tripp likes Paula, then fears she's getting too close, then is angry when he finds out she was hired to date him; Paula considers Tripp just a client, then really likes him, then must make amends. No one is ever in the same emotional place long enough for us to relate to them, and half the time we know they're being lied to anyway.

I take issue with the film's curiously high number of "When Animals Attack" scenarios, too, with Tripp running afoul of everything from chipmunks to dolphins. Why, movie? Why?

But it's fun stuff, overall, inconsequential and fluffy and not too cheesy until the end. Among the 13,782 romantic comedies that will be released this year, surely this one is among the top 5,000 or so.